1. Field of the Invention
The present invention relates to ion generating apparatus. In particular the present invention relates to ion generating apparatus utilizing a thin disk shaped plasma.
2. Prior Art
Recent ion engine research has focused on the use of time-varying (wave) electric energy or radio frequency waves, particularly microwave and UHF waves, for electric propulsion engines or other ion generating apparatus. Specific research projects presently being conducted involve utilizing rf (Divergilio, W., MSU/NASA Workshop, East Lansing, Mich. Feb. 24-25, 1982) Loeb, H. W., "State of the Art and Recent Developments of the Radio Frequency Ion Motors," AIAA Paper 69-285 March 1969; Noriyuki Sakudo, Katsumi Tokiguchi, Hidemi Koike, Ichiro Kanomata, "Microwave Ion Source", Review of Scientific Inst. 48, July 7, 1977; VHF (Nakanishi, S., MSU/NASA Workshop, East Lansing, Mich., Feb. 24-25, 1982) and microwave (Divergilio, W., MSU/NASA Workshop on Advanced Propulsion Concepts Using Time Varying Electromagnetic Fields, East Lansing, Mich., Feb. 24-25, 1982) electric energy sources. These engine concepts possess certain advantages over the more conventional well-developed direct current ion source apparatus. For example, time varying electric ion sources appear to (1) improve overall system efficiency (low eV/ion); (2) allow high ion beam densities when accelerated; (3) yield longer life engines due to the absence of metal cathodes in the discharge region; and (4) result in simplified overall system design. The same apparatus can also used for free radical or ion irradiation of various materials rather than as ion engines. In each instance the radio frequency wave apparatus are complex.